The present invention relates generally to roofing seals and, more particularly, to an improved method for temporarily sealing a roofing membrane to a roof substrate. The present invention finds particular utility in the field of replacement of roofing, or reroofing.
When an existing roof is replaced on a structure, one or more elastomeric, flexible membranes are commonly used as the top layer of the new roof to provide a watertight and weatherproof barrier for the top surface of a roof. The existing roof typically includes a lower base or support member, such as corrugated steel decking, and one or more layers of insulation which cover the base. These layer(s) of insulation are covered with a waterproof layer which may include one or more layers of roofing felt embedded in either hot tar or asphalt to form a substantially water-impervious coating. Loose gravel may be scattered across the top of this layer to improve its resistance to abrasion and ultraviolet radiation. Through repeated exposure to weather, the impervious asphalt-gravel layer may break down and water may permeate through the various roof layers, causing leakage. The old roof layers are removed and new insulation is applied to the decking along with a new top waterproof layer which includes one or more waterproof, elastomeric membranes. These membranes are sealed in various manners to the insulation layers beneath them to form an impervious top roof layer. The roofing membrane is applied to the roof in an area which is only large enough to be completed during the working hours.
When the roof area is large enough that the entire extent of the new insulation layers cannot be installed and covered with a membrane within the working hours of a single day, the flexible roofing membrane must be secured to the roof in a manner to prevent the wind from lifting it up along an open edge, as well as to prevent the infiltration or migration of water underneath the membrane. To prevent this from occurring, the membrane must be temporarily sealed to the roof substrate along its leading edge.
One practice presently followed in the art involves sealing the membrane to the roof with an expandable foam which is substantially impervious to water. This practice requires that a first layer of the foam having a preselected width be applied to the roof substrate. The leading edge of the roofing membrane is carefully embedded into the first foam layer, and a second layer of foam is subsequently applied to the top of the roofing membrane along its leading edge and also to a portion of the first foam layer to create an overlapping foam seal which is impervious to moisture. When work is resumed, the leading edge of the membrane sealed to the first and second foam layers is cut off and discarded. This procedure not only wastes material because the membrane is cut, but also is time intensive because it requires the application of two layers of foam. Additionally, the membrane is adhered to the first foam layer for approximately only one-half of the width of that first foam layer.
Another practice commonly used in the art involves sealing the membrane to the roof with a layer of plastic cement or hot asphalt. This practice is also labor-intensive and also wastes material in that the membrane must be cut away from the adhesive layer.
The present invention is therefore directed to a method which overcomes these disadvantages and accordingly concerns itself with the establishment of a temporary, or night seal between the roofing membrane, and the existing roof substrate in which the membrane may be easily removed from the roof substrate and in which the membrane does not have to be cut to remove the temporary seal. This method thus reduces the amount of time required to remove the temporary seal and resume work as well as saves on materials.
Such a temporary seal is accomplished by folding the roof membrane onto itself along a preselected foldline to define a leading edge of the membrane and applying a layer of foam adjacent the membrane leading edge such that the foam adheres to both the roof substrate and the underside of the membrane. The foam is allowed to expand upwardly against the membrane and outwardly from its leading edge to form an impervious wedge-shaped foam layer. The membrane can be easily peeled away from the membrane to remove it from the foam and the installation of the replacement roof and membrane resumed.
Accordingly, it is an object of the present invention to provide a method for applying a temporary, or night seal to a roofing membrane in which the membrane is folded over upon itself and an impervious layer of an expandable foam is formed at the leading edge of the membrane and the roof substrate which seals the interface of the membrane and the roof substrate from water or inclement weather.
It is another object of the present invention to provide a method for temporarily sealing a roofing membrane to the roof substrate in which the membrane is not cut.
It is a further object of the present invention to provide a method for applying a flexible, elastomeric membrane to a roof substrate in which the flexible membrane is unrolled onto and adhered to a portion of the roof substrate, the leading edge of the membrane is folded upon itself along a foldline extending between two opposing edges of the roof, and a sealing member in the form of an expandable foam is laid down proximate to the exposed leading edge of the membrane, the sealing member extending between the roof substrate and the underside of the membrane, the foam being allowed to expand into a substantially impervious wedge and to adheringly contact the roof substrate and the membrane, and the membrane being peeled away from the foam wedge when work is to resume on the roof.
These and other objects of the present invention will become more readily apparent from a reading of the following detailed description taken in conjunction with the accompanying drawings wherein like reference numerals refer to like parts.